Mass testing will begin in Merthyr Tydfil this Saturday, the Welsh Government has confirmed.
The county is the first part of Wales to have the scheme rolled out, with the help of 165 military personnel.
It is hoped testing will find people without symptoms who may be infected, so they can self-isolate.
Merthyr Tydfil had the highest case rate in UK at the start of November and is still among the worst affected areas in Wales.
Health Minister Vaughan Gething said all residents in the county will be offered repeat Covid testing from Saturday, even if they do not have symptoms.
The first site will open at Merthyr Tydfil Rhydycar leisure centre on Saturday, with other sites due to open later this month.
A pilot scheme in Liverpool saw 23,000 tested and found 154 cases and is planned for sixty-seven areas further areas in England.
Mr Gething said armed forces personnel, who have been in Merthyr since last week, would provide “logistical support”.
In a statement, the Labour Welsh minister told Senedd members that Merthyr would provide further information on more potential mass testing in Wales.
He said the scheme aims to “protect Merthyr and residents at highest risk” and “test the maximum number of inhabitants living in Merthyr Tydfil to identify the virus”.
Welsh Secretary Simon Hart tweeted that he had approved a military request for support.
“We’re working hand in hand with Merthyr Tydfil Council and Welsh Government to defeat this virus,” the Conservative UK government minister said.
Mass testing uses lateral flow tests which intend to produce a result within 20-30 minutes.
There are plans for the tests to be used to help students go home safely for Christmas.
There had been 458 cases in Merthyr in the week up to 1 November and the case rate rose as high as 759 cases per 100,000.
The proportion of positive results from tests taken was also high – accounting for nearly a third of people tested.
Those case rates have since come down and Merthyr has been overtaken by Blaenau Gwent and Neath Port Talbot.
Up to 14 November the case rate was 286.8 per 100,000, with 173 cases across the county but is still above the Wales average.
Gurnos, which has had 44 cases in the last week, is still in the highest districts of Wales when local case rates are broken down.
“If successful, I hope ministers will work positively with partners to ensure this is rolled-out to other high incidence areas in Wales to ensure we have can gain more control of this virus and return some more normality to people’s lives.”